I was polite when I returned the one with the dead pixels, and the one with the hardware fault. I wasn't really expecting any sort of compensation/good-will gesture but a friend who works at an apple store (sadly not the one near me) told me that in such circumstances they offer little things like £10 itunes vouchers or store credit or some acknowledgment that the customer had been inconvenienced.

THEN of course you read on various forums about people being recompensed for their troubles. I just thought to get some opinions before I acted, thus saving Apple and myself time and hassle